Many pathogenic viruses have developed strategies to evade recognition and elimination by host immune systems. Such strategies include high mutation rates of envelope glycoproteins, glycosylation of envelope proteins, and conformational masking—whereby conserved portions of viral proteins, such as those involved in key functions such as receptor binding, are “masked” such that they are poorly recognized by, or evade recognition by, antibodies. Such conformational masking poses a major problem in the development of vaccines based on viral proteins. Hence there is a need in the art for methods of producing engineered viral proteins, and complexes of viral proteins, that have enhanced immunogenicity and enhanced effectiveness as vaccines.